KVPY SX SB Exam 2012 Question Paper

Question : 39 of 120

Marks: +1, -0

A parent nucleus X is decaying into daughter nucleus Y which in turn decays to Z. The half lives of X and Y are 40000 years and 20 years respectively. In a certain sample, it is found that the number of Y nuclei hardly changes with time. If the number of X nuclei in the sample is

4 × 10^20

, the number of Y nuclei present in it is

$2×10^17$
$2×10^20$
$4×10^23$
$4×10^20$

Validate

Solution:

In radioactive equilibrium
rate of decay of X = rate of decay of Y

\λ_x\N_x=\λ_y\N_λ

\N_x/\T_x=\N_y/\T_y

Go to Question:

Prev Question

Next Question